This application is related to currently pending U.S. patent application Ser. No. 11/576,152 filed Mar. 28, 2007.
The present invention relates to an integrated circuit (IC) device and in particular relates to a method of protecting the IC device from an external environment including electromagnetic interference (EMI) or radio frequency interference (RFI).
Integrated circuit devices such as magnetic random access memory (MRAM) may be subject to error in the presence of stray or externally applied electromagnetic fields other than applied write fields. Such stray fields can originate from a variety of sources including electronic devices such as computers, displays, etc. and may have sufficient magnitude to switch the logic state of one or more memory cells even in the absence of a write field.
Integrated circuit devices are commonly protected from the external environment by encapsulation with an epoxy material or transfer molding a thermoplastic resin around the device. However, the epoxy or plastic encapsulent does not provide effective shielding from radiation such as EMI or RFI.
Some conventional shielding systems use a conductive metallic enclosure that surrounds the circuit to be shielded. Other systems use magnetic foils to shield the device from magnetic fields. However, all of the known solutions have some draw-backs. For instance use of a conductive metal enclosure adds to the overall size of the package and requires an additional soldering process to attach the enclosure to the device with heat generated by the additional soldering process potentially damaging the device. Use of magnetic foils on the other hand gives rise to serious interface delamination issues particularly when double foils are used in a cladding structure.
Therefore a need exists for a cost effective component level shielding process that can be used in a variety of circuit devices with any semiconductor die size.